1. Field
The described technology relates to an organic light emitting diode (OLED) display improving a drop of a common voltage ELVss in a cathode in a front light emitting structure.
2. Description of the Related Technology
An organic light emitting diode display is a self emissive display that displays an image using an organic light emitting diode for emitting light. Light is generated by energy created when excitons, that are generated by coupling of electrons and holes within an organic emission layer, drop from an excited state to a ground state, whereby the OLED display displays an image using the generated light.
Organic light emitting diode (OLED) displays can be classified into a rear light emitting type and a front light emitting type. In the rear light emitting type, the cathode functions as a reflective layer. Accordingly, the cathode is typically made of a material having low resistance and a large thickness such that an IR drop of the common voltage ELVss can be minimized in the cathode. In the front light emitting type, the cathode functions as a transmissive layer, and is generally formed of a transparent material having a small thickness and low resistivity to increase its transmittance. Accordingly, the voltage drop is generally increased in the cathode due to the high resistance. The rear light emitting type can be more advantageous for an organic light emitting diode (OLED) display of a large size (for example, more than 10 inches).
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.